How do I perform the dumbbell squat?

When the femur (thigh-bone) is parallel to the floor, come back to your initial position, extending your calves.

Don’t forget to exhale at the end of the motion.

via: Strength Training Anatomy, 2nd Edition

In order to reach a great performance, dumbbell squats are usually done using medium weight dumbbells. Your muscles work together in order to keep the correct motion of the body, thus using medium weight dumbbells in the squats will get you the best results.

You must know that this exercise focuses particularly on the quadriceps and its subgroups: rectus femoris, vactus lateralis, vactus intermedius. Also, these squats focus on the gluteal muscles (gluteus medius and gluteus maximus).